How EMG Biofeedback and PT May Help TMJ

Temporomandibular dysfunction is more commonly known as TMD or TMJ. This sometimes debilitating condition is associated with:

• Jaw pain
  
• Pain around the ears
  
• Facial pain
  
• Headaches
  
• Difficulty chewing
  
• Clicking or popping in the jaw with movement

TMD has been said to affect 5-12% of the population. However, my professional experience as a practicing physical therapist has led me to believe this number is greatly underestimated. I believe a much larger percentage of individuals are afflicted with the condition and fail to seek treatment. (1) Causes of TMD include genetics, trauma, arthritis, disk degeneration, repetitive movements, and abnormal postures. To this end, in my professional experience in treating the disorder, I believe posture is the primary factor in developing jaw pain.

Positional Causes of TMJ

Research has shown that the muscles involved in opening and closing your jaw change in length and action on the joint with head position. (2) The typical forward head posture with rounded shoulders causes changes to the temporomandibular joint (the two joints connecting the jawbone to the skull). This takes up free space in the joint that allows for normal function. Additionally, forward head posture causes an internal conflict with muscles of chewing. This strain over a period of time can initially result in an audible click or pop. While this may not be painful, if left untreated it could become a problem. 

Potential for EMG to Manage TMJ Symptoms

Surface electromyography (EMG) is effective in the diagnosis of TMD. However, surface EMG can also have a positive impact on alleviating the symptoms of TMD. There is ample evidence showing changes in muscle activity between neutral posture and a forward head posture. (3) This is most notable when assessing posture with a computer and wearable EMG sensor. Therefore, cervical muscles in the back of the head and neck increase in activity as the head moves forward and the trunk assumes the “hunched” position.

Most of us have no idea we are doing this. When prompted we can correct it, but this correction will only last as long as we are aware. We can use all sorts of external supports, but often these too have their limitations. Thus, by combining external supports with surface EMG we can help improve postures in order to reduce pain.

Placing a surface electrode on the back of the neck below the base of the head and measuring muscle activity of the cervical extensors can alert the user of poor posture when seated at a computer or using a handheld device. Once alerted the user can adjust the posture to decrease muscle activity and eliminate the signal. Eventually, the user can become conditioned and will set off the signal of the surface EMG less frequently. Essentially the surface EMG can be thought of as your posture coach, letting you know when you are not performing up to par. So, this is effective for traditional workstations, laptops, hand-held device use, and even eating.

References

1. Prevalence of TMJD and its Signs and Symptoms. National Institute of Dental and Craniofacial Research. https://www.nidcr.nih.gov/research/data-statistics/facial-pain/prevalence. Accessed October 23, 2018.
2. Goldstein L. TMD/Facial Pain and Forward Head Posture. Practical Pain Management Website. https://www.practicalpainmanagement.com/pain/maxillofacial/tmj/tmd-facial-pain-forward-head-posture. Updated January 4, 2012. Accessed October 23, 2018.
3. Song J-I, Kang S-Y, Park J-H, Cynn H-S, Jeon H-S. Influence of Forward Head Posture on Electromyography Activity of Hyoid Muscles During Mouth Opening. Physical Therapy Korea. 2015;22(1):103-109. https://www.e-sciencecentral.org/articles/SC000015928. Accessed October 23, 2018.

About the Author

Corey Sylvain is a physical therapist with 16 years of experience working in outpatient orthopedic and home health care. Additionally, he has advanced skills in manual therapy completing a residency program for manual therapy in the Kaltenborn approach. In addition to traditional physical therapy practice, he holds a masters degree in public health. Likewise, outside of his professional role he values living a healthy active lifestyle and the importance of family.

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